docs: def _setup(self, name=None):
          """
          Load the settings module referenced by env_var. This environment-
          defined configuration process is called during the settings
          configuration process.
          """
          envvar = self.__dict__['env_var']
          if envvar:
              settings_file = os.environ.get(envvar)
          else:
              settings_file = self.__dict__['file_path']
  
          if not settings_file:
              msg = ("Requested settings, but none can be obtained for the envvar."
                     "Since no config filepath can be obtained, a default config "
                     "will be used.")
              logger.error(msg)
              raise OSError(msg)
  
          self._wrapped = Settings(settings_file)